<html dir="ltr">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<style type="text/css" id="owaParaStyle"></style>
</head>
<body style="" fpstyle="1" ocsi="0">
<div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 13px;">
<div style=""> </div>
<div style="font-family: Times New Roman; color: #000000; font-size: 16px">
<hr tabindex="-1">
<div id="divRpF433132" style="direction: ltr; "><font face="Tahoma" size="2" color="#000000"><b>From:</b> John Brown<br>
<b>Sent:</b> Thursday, December 08, 2011 4:20 PM<br>
<b>To:</b> Kirk Kirkpatrick; 1st-mile-nm@mailman.dcn.org<br>
<b>Subject:</b> RE: [1st-mile-nm] Agave Broadband News<br>
</font><br>
</div>
<div></div>
<div>
<div style="direction:ltr; font-family:Tahoma; color:#000000; font-size:13px">
<div style="">I responded to the Press Release post. My comments: (Note that I don't go out as Mr. Kirkpatrick did and say that he is a stinky poo-poo head)</div>
<div style=""><br>
</div>
<div style="">1. Document that MVDDS is not NEW technology as the Press Release leads one to believe.</div>
<div style=""> Mr. Kirkpatrick comments further support that the technology is not "NEW" but has been around for at least 2 decades</div>
<div style=""><br>
</div>
<div style="">2. Much of the data with respects to what can the license holder do or not do is cut and past from the FCC website and the electronic version of the license.</div>
<div style=""> The data is fairly easy to get to and if people want URL's to the specifics I'm happy to provide.</div>
<div style=""><br>
</div>
<div style="">3. Wikipedia stated that HyperCable was from the 80's. If they are wrong, then someone should fix it.</div>
<div style=""><br>
</div>
<div style="">4. The technology is ONE-WAY, pursuant to the FCC license. Technically speaking this means that the end subscriber may not transmit on the licensed MVDDS frequency.</div>
<div style=""> As I stated and as Mr. Kirkpatrick stated in response and as the FCC license states, to use this technology as a TWO-WAY solution will require a different path away from the end subscriber.</div>
<div style=""> Yes, this could be a 3G Cellular Phone based path, it could be a WiFi, or something else in the unlicensed 2.4 or 5.x or other frequency blocks.</div>
<div style=""> I caution that if it is in the 2.4 or 5.x blocks that the noise floor in ABQ is pretty HIGH, and that current City of Santa Fe ordinances prohibit the placement of antennas without prior approval by the City.</div>
<div style=""> This COULD lead to frequency congestion and thus packet loss. Same holds true for the 3G return path solution.</div>
<div style=""><br>
</div>
<div style="">5. I also caution that focusing on the downlink speed is only a partial answer. TCP requires a reasonable return path. If that return path has delay, congestion, packet-loss, etc then</div>
<div style=""> there will be problems with the effective download speed perceived by the end user. Since the packet flow is ASYMMETRICAL, the asymmetry of the path will have to be </div>
<div style=""> carefully managed. In general this is the BDP (Bandwidth Delay Product). </div>
<div style=""><br>
</div>
<div style="">6. BDP in part causes packet buffer sizing issues. Packets need to be buffered until the ACK is received back from the end subscriber. If that ACK is lost, then the packet </div>
<div style=""> must be resent. Larger buffers require more RAM on the networking devices, which in turn causes a higher BOM (Bill of Materials) cost for the equipment. The larger the pipe the larger the buffers have to be, unless the </div>
<div style=""> return path is really really good.</div>
<div style=""><br>
</div>
<div style="">7. It would interesting to know what the supported MTU is for the MVDDS technology on the RF interface. What overhead exists in addition to the IP header. Is there any SAR performed on the payload.</div>
<div style=""><br>
</div>
<div style="">8. The single license issue.. The FCC has presently granted a single license for a single transmitter. Based on that public government data, my statement that should this transmitter fail, users would loose this service, is a reasoned statement.
Yes, Mr. Kirkpatrick is correct that they could request and be granted additional transmitter licenses by the FCC. But today, they have a single license for a single transmitter.</div>
<div style=""><br>
</div>
<div style="">9. "Shared bandwidth" In looking at the bandwidth delivered to a subscriber, Cable and RF (cable is RF as well) are shared. DSL, T1, DS3 are point to point. Being that there is a dedicated path between the specific end-subscriber and the first
level aggregation equipment. Cable / RF based systems are shared. Certain Fiber based systems, ala PON are also shared. The "sharing" is in some cases done with TDM.</div>
<div style=""><br>
</div>
<div style="">10. I don't see a screen shot at the URL posted by Mr. Kirkpatrick for the real-world bandwidth in ABQ. </div>
<div style=""> Here is a recent one from one of our residential subscribers <span class="Apple-style-span" style="font-family:Times; font-size:medium">http://www.speedtest.net/result/1626433361.png</span></div>
<div style=""><span class="Apple-style-span" style="font-family:Times; font-size:medium"><br>
</span></div>
<div style=""><span class="Apple-style-span" style="font-family:Times; font-size:medium">11. It will be interesting to run pathchar, iperf and other similar tools on this type of network.</span></div>
<div style=""><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size:medium"><br>
</span></font></div>
<div style=""><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size:medium">12. According to the MDSA website "http://www.mdsamerica.com/index.cfm/technology/mdsa-mvdds-gigaband/" I would like clarification on the "..
to avoid fixed IP addresses." Does this prevent the end subscriber from having a static publicly routed IP address, without any form of NAT/PAT. If yes, then this would prevent customers from having their own server(s) onsite.</span></font></div>
<div style=""><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size:medium"><br>
</span></font></div>
<div style=""><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size:medium">Cheers...</span></font></div>
<div style=""><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size:medium"><br>
</span></font></div>
<div style=""><font class="Apple-style-span" face="'Times New Roman'" size="4"><span class="Apple-style-span" style="font-size: 16px;"><font class="Apple-style-span" face="Times"><span class="Apple-style-span" style="font-size: medium;"><br>
</span></font></span></font></div>
</div>
</div>
</div>
</div>
</body>
</html>